Higher Heating Value Research Articles

Co-hydrothermal carbonization of polyvinyl chloride and rice straw for solid fuel production: Investigation into effect of solid to water ratio using box Behnken design and response surface methodology

Co-hydrothermal carbonization (co-HTC) of polyvinyl chloride (PVC) and biomass is a promising method for the responsible disposal of both waste streams. Temperature and holding time were considered as the dominant factors in the production of chlorine-free and energy-dense hydrochar. However, the effect of solid-to-water ratio (S:W), which determines wastewater generation remains unclear. This study investigated the effect of S:W ratio and its synergistic effect with temperature and holding time on dechlorination efficiency (DE), higher heating values (HHV), and energy yield (EY) of hydrochar from blended PVC and rice straw (RS) using design experiment methodology. Two optimal conditions for the highest DE and HHV were identified as 250 °C-60 min − 1:5 and 250 °C-90 min-1:10, respectively. The likely optimal condition for EY was 220 °C-60 min-1:5. Statistically significant synergistic interaction was found between temperature and holding time in terms of the DE, although the effect of holding time became less pronounced with increasing temperature. RS was found to wrap the PVC intermediates during co-HTC, resulting in co-hydrochars with identical surface functional properties to RS-derived hydrochar. Notably, this study found that the S:W ratio is proportional to the enhancement of DE and HHV, as well as the removal of HCl-soluble alkali and alkali earth metals (AAEMs). Lowering the water content in co-HTC engenders similar behavior to pyrolysis, where the released HCl played an autocatalytic effect in the dechlorination of PVC, thus enhancing the DE in the elimination pathway.

Investigating chemical changes, material properties, and off-gas emissions in sewage sludge through thermal plasma treatment.

This study aimed to investigate the thermal plasma treatment of sewage sludge as an alternative waste management solution. Samples were collected from a sewage treatment facility in São Paulo, Brazil, and subjected to thermal treatments in a furnace at temperatures of 400, 600, 800, and 900°C to assess moisture content, mass loss, and ash composition. Subsequently, the samples were processed in a thermal plasma reactor operating at an average power of 30kW. Comprehensive characterization using X-ray fluorescence, X-ray diffraction, and Fourier-transform infrared spectrometry revealed the presence of oxides, particularly those of K, Ca, and Fe, which influence material melting points. Plasma treatment significantly reduced the mass and volume of the sewage sludge, losing up to 72 and 90%, respectively. Gas analysis indicated syngas (CO+H2) production with a high heating value (HHV) of 9049kJ/m³, underscoring the energy recovery potential. Leaching and solubility tests confirmed the treated material as inert and suitable for safe disposal or reuse in construction, with chemical and structural analyses showing that the vitrified material was primarily composed of SiO₂. These findings highlight the effectiveness of thermal plasma treatment in achieving sustainable sewage sludge management by combining waste reduction, energy recovery, and the production of environmentally safe by-products.

Transforming sludge into energy: impact of blend percentage on energy recovery potential and environmental benefits of co-combustion of wastewater sludge and coal in Brazil.

Proper waste management and sustainable energy production are crucial for human development. For this purpose, this study evaluates the impact of blending percentage on energy recovery potential and environmental benefits of co-combustion of wastewater sludge and Brazilian low-rank coal. The sludge and coal were characterised in terms of their potential as fuel and co-combustion tests were carried out in a pilot-scale bubbling fluidised bed focused on the influence of the percentage of sludge mixture on the behaviour of co-combustion with coal in terms of flue gas composition and fluidised bed temperature stability. Sludge has a higher heating value (16.276MJ/kg) than coal (15.486MJ/kg) and a higher fuel ratio (8.48 vs. 0.21). The O2 and CO2 levels found in the co-combustion tests, together with a very low CO concentration, indicate good combustion. However, the NOx emission was considerable, varying from 825.2±94.5 to 1,320.5±33.8mg/m3 (O2ref=7%), pointing to the need for actions to reduce atmospheric pollution. Coal had higher ash content (52.64% vs. 25.00% d.b.). The temperatures in the bed region and in the combustion region showed similar behaviour for all the fuels. The addition of sewage sludge to mineral coal reduced the ash content without increasing the ash fusibility risk in the combustion temperature range evaluated. These findings suggest that sludge addition in co-combustion with coal offers promising results for both energy production and environmental sustainability.

Urea enhances the yield and quality of bio-oil produced from corncob through pyrolysis

As global demand for fossil fuels rises amidst depleting reserves and environmental concerns, exploring sustainable and renewable energy sources has become imperative. This study investigated the pyrolysis of corncob, a widely available agricultural waste, using urea as a catalyst to enhance bio-oil production. The aim was to determine the optimum urea concentration and pyrolysis temperature for bio-oil yield from corncob. A series of experiments were conducted at varying temperatures (350 °C, 400 °C, and 450 °C) and urea concentrations (0%, 5%, 10%, 15%, and 20%) to assess their impact on bio-oil yield, chemical composition, and energy content. Fourier Transform-Infrared Spectroscopy, Gas Chromatography-Mass Spectrometry (GC–MS), Ultimate Analysis, and High Heating Value (HHV) analyses were employed to evaluate the quality of bio-oil produced. Results indicate that a 10% urea concentration at 400 °C improves bio-oil yield from 49.33 to 54.66%. FT-IR analysis revealed enhanced absorption in key functional group regions, including O–H, N–H, C–H, C=O, and C–O, for bio-oil treated with 10% urea compared to untreated bio-oil. Ultimate analysis indicates that urea treatment improved bio-oil quality by increasing carbon (84.80–86.40%), nitrogen (2.29–2.68%), and oxygen (7.22–8.31%) contents while reducing hydrogen (5.09–2.38%) and sulfur (0.62–0.20%) contents, with improvement in the HHV from 36.12 to 37.12 MJ/kg. GC–MS analysis further revealed the presence of nitrogenous compounds, notably siloxanes in the bio-oil produced with urea infusion. This research highlights the potential of urea-catalyzed pyrolysis as a viable method for converting corncob into high-energy bio-oil, offering a promising alternative to traditional fossil fuels while addressing sustainability and environmental impact challenges.

Thermal analysis of thermally treated spruce wood after its accelerated aging

Abstract In contrast with untreated wood, thermally treated wood has a much longer lifespan, and compared to chemically modified products, its valorization after the end of the life cycle is much easier. We investigated the effect of thermal modification of spruce wood at temperatures of 160, 180, and 210 °C, the industrial product Thermo-D, and the effect of accelerated aging (600 h in Xenotest chamber, wet mode) on its energy properties. We used calorimetry, elemental analysis (CHNO), thermal analysis—thermogravimetry (TG, DTG), and differential scanning calorimetry (DSC). The results of calorimetry show that the higher heating values (HHV) increased significantly because of the thermal modification temperature. We noticed a similar trend after accelerated aging (HHV = 20,061–21,515 (kJ kg−1)). Relations between experimentally determined HHV values and values calculated from chemical composition and elemental composition show a very good mutual correlation (r = 0.8876–0.9710). Thermal analysis shows a higher content of thermal energy in modified and aged wood in comparison with untreated sample. The obtained knowledge can be applied for the energy use of Thermowood at the end of its life cycle, depending on the conditions of its treatment, and it can also be used for fire risk assessment of Thermowood products.

Optimized hydrothermal carbonization of chicken manure and anaerobic digestion of its process water for better energy management.

Modern poultry production is faced with the challenge of properly managing its associated wastes, in particular chicken manure (CM). There is a need to improve the management of CM through conversion processes that allow the production of value-added products, particularly for energy purposes, such as hydrothermal carbonization (HTC) and anaerobic digestion (AD). The objectives of this study were: i) to optimize the CM-HTC, using response surface methodology with simultaneous optimization of mass yield and higher heating value (HHV), and ii) to evaluate the biomethane potential of the process water generated from hydrochar production under the optimized condition. An analysis of the overall energy potential was also performed. The optimal condition for HTC was 234°C for 30min, resulting in hydrochar with an HHV of 14.88±0.22MJ/kg and a mass yield of 50.00±3.13wt%. The cumulative methane yield was 179.2±13.1 NmL CH₄/g VSadded and 255.5±14.5 NmL CH₄/g VSadded for process water at 180°C and 234°C, respectively. The addition of hydrochar improved the methane yield by 49.6±10.8%, indicating that this is a valuable option for energy recovery from CM. Overall, the HTC-AD integration approach achieved an energy recovery potential of more than 79%, offering an efficient strategy for CM valorization.

Enhancing biofuel pellet quality using torrefaction and co-pelletization of palm kernel shell and empty fruit bunch.

Palm kernel shell (PKS) and empty fruit bunch (EFB) are potential biomass resources for producing solid biofuel for energy applications. However, raw EFB and PKS are not uniform in size and pose rotting behavior. Torrefaction and co-pelletization are both effective methods to improve their combustion and mechanical characteristics. This study aims to investigate the effect of torrefaction temperature and the blending ratio of PKS and EFB on the mechanical and combustion characteristics of co-pellets. Initially, PKS and EFB underwent torrefaction process for 30min at three different temperatures (210°C, 240°C, and 270°C). Then, both torrefied PKS and EFB were blended at five different ratios (0:100, 25:75, 50:50, 75:25, 100:0) with carboxymethyl cellulose as a binder (10% by weight). The results showed that pellet produced at higher torrefaction temperature at 270°C resulted in an increment of the higher heating value (HHV) but weaker mechanical strength. Pellet with a blending ratio of PKS to EFB (75:25) torrefied at 240°C showed the comparatively best pellet quality in terms of HHV (17.94MJ/kg), high tensile strength (3.5MPa), low ash content (3.97 wt%), and the lowest density changes (0.66%), which satisfy the standard requirements for commercial pellets, indicating that a high-quality biofuel pellet can be produced using torrefaction and co-pelletization.

Copper Benzene‐1,3,5‐Tricarboxylate Metal‐Organic Framework Performance as a Heterogeneous Catalyst for Biodiesel Production

ABSTRACTThe increasing demand for sustainable fuels has driven extensive research into biodiesel production, which typically relies on the use of active catalysts to facilitate the transesterification of oils. While homogeneous catalysts are commonly employed, they pose challenges in terms of recyclability and environmental impact, leading to growing interest in heterogeneous catalysts. Among these, metal‐organic frameworks (MOFs) have gained attention due to their high surface area and tuneable properties. This study investigates the performance of a copper benzene‐1,3,5‐tricarboxylate (CuBTC) MOF as an effective heterogeneous catalyst for biodiesel production. CuBTC was synthesised via solvothermal method and thoroughly characterised using scanning electron microscopy to examine the morphology, powder X‐ray diffraction to determine the crystalline structure, and Fourier transform infrared spectroscopy to identify the functional groups. The synthesised CuBTC has an octahedral morphology and successfully catalysed biodiesel production with unsaturated fatty acids within the C16 to C18 range, achieving a yield of 78.6% using 1 wt.% CuBTC and a 10:1 methanol‐to‐oil molar ratio. The iodine value of the produced biodiesel was 59.3 g I/g, and the higher heating value was 39.2 MJ/kg. Recycled CuBTC maintained its efficacy, yielding 76.6% and 63.4% fatty acid methyl esters in the first and second recycling runs, respectively, with 16.6% and 15.3% of C16 to C18 fatty acids. The produced biodiesel met quality standards outlined in EN 14214, highlighting CuBTC's potential for sustainable biodiesel production.

Optimization of pyrolysis process parameters for optimal high heating value of biochar produced from rice straw

The harvest of rice leaves abundant biowaste and its utilization is being researched. Hence, this paper targets the conversion of rice straw into biochar. In this study, the vacuum-assisted intermediate pyrolysis process is used to convert the rice straw biowaste into biochar, which can be used as a fuel. The produced biochar is studied for the biochar yield and energy yield. It is further analyzed for the high heating value (HHV). This experimental investigation optimizes the processing parameters such as time and temperature to obtain the optimal HHV. The response of HHV is maximized using response surface modeling (RSM) based on a central composite design (CCD) matrix. This technique systematically investigated the influence of continuous parameters on the dependent variable. As a result, the time and temperature and their interaction have the most significant effect on the HHV of the biochar obtained from two different amounts of feedstocks. The optimal response obtained for HHV1 is 21.45 MJ/kg at time 47 min and temperature 397 °C, whereas HHV2 is 19.43 MJ/kg at time 51 min and temperature 405 °C. The Fourier transform infrared (FTIR) analysis is further used to characterize the biochar obtained at optimized parameters.

A Solar-Heated Phase Change Composite Fiber with a Core-Shell Structure for the Recovery of Highly Viscous Crude Oil.

Due to the high viscosity and low fluidity of viscous crude oil, how to effectively recover spilled crude oil is still a major global challenge. Although solar thermal absorbers have made significant progress in accelerating oil recovery, its practical application is largely restricted by the variability of solar radiation intensity, which is influenced by external environmental factors. To address this issue, this study created a new composite fiber that not only possesses solar energy conversion and storage capabilities but also facilitates crude oil removal. PF@PAN@PEG was obtained by coaxial electrospinning processing, with PEG within PAN fibers, and a coating layer was applied to the fiber surface to impart oleophilicity and hydrophobicity. PF@PAN@PEG exhibited a high latent heat value (77.12 J/g), high porosity, and excellent photothermal conversion and oil storage capabilities, significantly reducing the viscosity of crude oil. PF@PAN@PEG can adsorb approximately 11.65 g/g of crude oil under sunlight irradiation. Notably, due to the encapsulation of PEG, PF@PAN@PEG can continuously maintain the crude oil at a phase change temperature by releasing latent heat under specific conditions, effectively reducing its viscosity with no PEG leakage at all. When solar light intensity varied, the crude oil collection efficiency increased by 21.99% compared to when no phase change material was added. This research offers a potential approach for the effective use of clean energy and the collection of viscous crude oil spill pollution.

Investigation of moisture content and higher heating value in refuse-derived fuel from agricultural residues using statistical modelling

<p>There is an increasing interest in using agricultural residues and wastes for energy production due to concerns regarding climate change and energy security issues. One of the alternative fuels considered is Refuse-derived fuel (RDF) from biomass, which has a Higher Heating Value (HHV) comparable to coal. This study aims to investigate the relationship between the moisture content and the HHV value. Palm kernel shells (PKS), coconut husks (CH), and coconut shells (CS) were blended at various ratios (10%–80%) and moisture levels (5%, 7%, 10%). The HHV was analyzed through a proximate analysis, with JMP Pro 17.0 modelling the HHV against the moisture content. Then, the Tukey-Kramer analysis identified the optimal energy ratio, thus providing insights into maximizing the RDF efficiency. The result showed that the highest HHV was 21.617 MJ/kg with the RDF2 formulation. Notably, the RDF2 energy content was less than 4% of that of coal, thus demonstrating the potential of utilizing agricultural waste to produce solid fuel with a positive environmental impact.</p>

Investigation of Menounat coal beneficiation – Bechar deposit, for super clean concentrate recovery

ABSTRACT Although Algeria’s coal reserves are 246 Tg, no coal field is operational since 1970, and almost all our energy sources are gas and oil. Regarding the strong demand for an affordable coke supply of the Algerian steel industry compounded by the many other social economic motives, the present study investigates, for the first time, the beneficiation of the Algerian coal in Menounat seam (Bechar, Abadla basin). Different characterization methods, for instance, petrographic, mineralogic, and thermal, were carried out to define significant constituents that may have influence on coal processing. Washability was analyzed by sink-floats tests that show negative results for physical cleaning applicability, whereas floatability was examined by release tests. Ultimate, proximate, and petrographic analyses confirm the rank that is high volatile bituminous coal with appreciable properties corresponding to low ash content less than 10%, around 3% of moisture, and high heating value above 6900 kcal/kg, while having high sulfur content of nearly 2% was the main environmental concern. Regardless of negative washability data obtained, froth flotation using fresh prepared emulsified diesel oil shows interesting result of a super clean concentrate with lower ash content down to 3% and sulfur content less than 1.3%.

Effect of Pretreatment on the Pyrolysis Kinetics of Corn Stalk: Comparison of Inert, Oxidative, and Wet Torrefaction

This study compared the pyrolysis behaviors of corn stalk (CS) and its torrefied biomass after inert torrefaction (IT), oxidative torrefaction (OT), and wet torrefaction (WT), focused on the kinetic parameters and reaction mechanisms. Inert and oxidative torrefaction reduced volatile matter while increasing ash content and fixed carbon. Wet torrefaction reduced both volatile matter and ash content while increasing fixed carbon. Three pretreatment methods decreased oxygen content, increased carbon content, and had a higher heating value. The materials were pyrolyzed in a thermogravimetric analyzer. For CS, the average activation energy (E) values calculated by the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunosen methods were 62.5 and 60.07 kJ/mol. IT and WT showed increased trend, with values of 81.58, 81.48 kJ/mol and 69.75, 67.58 kJ/mol respectively. Conversely, OT decreased with the E values of 57.39 and 56.2 kJ/mol. Pyrolysis was divided into two stages based on various conversion rates (α) using Malek and Coats–Redfern methods. When α was below 0.5, a one-dimensional diffusion mathematical model described the pyrolysis process. When α was beyond 0.5, the pyrolysis of CS conformed to the cylindrical symmetric three-dimensional diffusion mathematical model, while IT, OT, and WT better fit the spherical symmetric three-dimensional diffusion mathematical model. However, the torrefaction atmosphere’s impact on the pyrolysis kinetic mechanism was limited, exhibiting no alterations in the diffusion model. Different torrefaction samples demonstrated a degree of homogeneity, considering the lower pretreatment temperatures and the economic feasibility of torrefaction atmospheres in oxidative torrefaction, coupled with the lowest activation energy of oxidative torrefaction products indicating more efficient pyrolysis, oxidative torrefaction was recommended as the torrefaction pretreatment process before pyrolysis engineering.

Catalyst-Free Depolymerization of Methanol-Fractionated Kraft Lignin to Aromatic Monomers in Supercritical Methanol

Lignin is considered a renewable source for the production of valuable aromatic chemicals and liquid fuel. Solvent depolymerization of lignin is a fruitful strategy for the valorization of lignin. However, Kraft lignin is highly prone to produce char (a by-product) during the hydrothermal depolymerization process due to its poor solubility in organic solvents. Therefore, the minimization of char formation remains challenging. The purpose of the present study was to fractionate Kraft lignin in methanol to obtain low-molecular-weight fractions that could be further depolymerized in supercritical methanol to produce aromatic monomers and to suppress char formation. The results showed that the use of methanol-soluble lignin achieved a bio-oil yield of 45.04% and a char yield of 39.6% at 280 °C for 2 h compared to 28.57% and 57.73%, respectively, when using raw Kraft lignin. Elemental analysis revealed a high heating value of 30.13 MJ kg−1 and a sulfur content of only 0.09% for the bio-oil derived from methanol-soluble lignin. The methanol extraction process reduced the oxygen content and increased the hydrogen and carbon contents in the modified lignin and bio-oil, indicating that the extracted lignin fraction had an enhanced deoxygenation capability and a higher energy content. These findings highlight the potential of methanol-soluble Kraft lignin as a valuable resource for sustainable energy production and the production of aromatic compounds.

Wood chemical characterization of Acacia mangium and Calophyllum brasiliense grown in plantation

This study aimed to characterize and compare the physical and chemical properties of wood from 15-year-old Acacia mangium and 16-year-old Calophyllum brasiliense plantation trees. Specific data is provided on basic density, extractives, holocellulose, lignin, ash content and the highest heating value, as well as the linear correlations between them were performed. We observed similar mean values of basic density, despite statistical differences were found in lignin and holocellulose contents. The results for the higher heating value (19.5 kJ kg−1) were noteworthy, as they are positively associated with the extractive content (8.3%) and lignin content (26.0%) of A. mangium and C. brasiliense, respectively. Furthermore, the relationships found between the basic density of C. brasiliense wood, and its chemical properties were different from those expected, suggesting that other analyses should be carried out on the wood in order to fully understand it. Both species demonstrate calorific values suitable for biomass production, suggesting the potential use of their residues for pellet and briquette manufacturing. The findings have provided valuable information on the quality and behavior of wood, especially to contribute to the sustainable use of forest resources.

Depolymerization of Kraft Lignin Using a Metal Chloride-Based Deep Eutectic Solvent: Pathways to Sustainable Lignin Valorization

Driven by the urgent need for sustainable alternatives to fossil fuels, the focus on the exploration of lignocellulosic biomass, particularly lignin, as a promising renewable feedstock for biofuels and high-value chemicals has intensified. This study investigated the depolymerization of KL using a DES comprising ChCl and ZnCl2. Our analysis systematically focused on the effects of reaction temperature, time, and the DES-to-lignin ratio on the yields and characteristics of the products. Optimal KL depolymerization was observed at a temperature of 190 °C and a duration of 8 h, yielding a maximum liquid product yield of 54.44% and RL yield of 45.56%. The results revealed that increasing the reaction temperature enhanced the depolymerization process owing to a reduction in the viscosity of the DES, which improved mass transfer and interactions with lignin. Under these optimal conditions, the molecular weight of the bio-oil was considerably lower (Mw = 1498 g/mol and Mn = 1061 g/mol) than that of the bio-oil obtained without DES treatment (Mw = 1872 g/mol and Mn = 1259 g/mol), indicating a more favorable molecular weight distribution with DES treatment. Furthermore, elemental analysis revealed a reduction in the O, N, and S contents of the RL following DES treatment, increasing the high heating value from 24.82 MJ kg−1 for the non-DES-treated RL to 26.44 MJ kg−1 for the DES-treated RL. These findings underscore the potential of the (ChCl:ZnCl2) DES as a sustainable and effective medium for lignin valorization, paving the way for the synthesis of high-quality biofuels and chemicals from lignocellulosic biomass.

Experimental Study of the Effect of Plastic Pyrolysis Oil on the Physical-Chemical Properties of Rubber Seed Biodiesel and Diesel Engine Performance using a Mixture of Plastic Pyrolysis Oil-Rubber Seed Biodiesel-Diesel Fuel

Rubber seed oil is a potential source of biodiesel, but its utilization is still limited. From previous research studies, the addition of Rubber Seed Biodiesel (RSB) to diesel will reduce engine performance and increase BSFC but can increase emissions. At the same time, plastic waste has posed a very serious environmental challenge due to its large quantity and suboptimal processing problems. Pyrolysis is considered to be an efficient solution for handling plastic waste, because it operates at low pressure and produces Plastic Pyrolysis Oil (PPO) as fuel. The success of research on converting plastic waste into fuel can be a solution to limited biodiesel raw materials, as well as a solution for handling plastic waste. From various previous studies it is known that PPO has a higher heating value than biodiesel, but biodiesel has a higher centane number. Based on these various symptoms, it is interesting to research the use of a mixture of RSB and PPO fuels, because they are thought to complement each other. In this research, PPO was added to RSB starting at 10%, 20%, 30% and 40%, then the physicochemical properties of each mixture were examined, it was found that PPO could increase the heating value, reduce viscosity, density and acid number, reduce the cetane number and reduces the oxidation stability of RSB. To test on a diesel engine, PPO was added to the diesel-RSB mixture. The diesel portion is set at 60%, while the RSB and PPO portions are varied starting from 40% RSB 0% PPO, 30% RSB 10% PPO, 20% RSB 20% PPO and 10% RSB 30% PPO. Diesel engine performance and emissions were investigated when PPO was added to the fuel mixture. The search results show that BTE decreased by 4% when using B10P30 compared to using pure diesel, but increased by around 30% compared to using RSB40 at full load. The addition of PPO to the Diesel-RSB mixture increases CO, HC and smoke emissions, but is still lower than pure diesel emissions.

Torrefaction Temperature Effects on Grindability of Wheat Straw Using TG-FTIR Analysis

Abstract Torrefaction used for pretreatment of biomass can enhance grindability along with significant reduction of energy consumption required for pulverization to aid in large-scale utilization of biomass energy. In this study, torrefaction experiments of wheat straw were conducted at different temperatures using an experimental furnace facility. The influence of torrefaction temperature on the grindability of resulting wheat straw was explored using a Hardgrove grindability index tester and thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR). Increase in torrefaction temperature significantly enhanced the carbon content of wheat straw and decreased oxygen content to result in decreased O/C ratio from 0.66 to 0.39. The calorific value increased by 24% from 15.42 MJ/kg to 19.17 MJ/kg. Increase in torrefaction temperature from 220 °C to 269 °C increased the grindability index from 29 to 115. The grindability of wheat straw can be controlled to values similar to that of coal by tuning the torrefaction temperature. The main gas components released during torrefaction were H2O, CH4, CO2, and CO. Thermogravimetric data showed 29% solid residue from the raw wheat straw. Increase in torrefaction temperature increased the solid residue to 41%. Pyrolysis of wheat straw at different torrefaction temperatures can be grouped into three stages of dehydration, rapid pyrolysis, and carbonization. This study reveals effective large-scale utilization of torrefied wheat straw biomass having high heating value of the solid fuel after torrefaction pretreatment.

Statistical models for predicting the higher heating value of torrefied kesambi leaves

The study investigates the effects of temperature and residence time on the energy density of kesambi leaves through experimental torrefaction, proximate analysis, and response surface methodology with a central composite design (RSM-CCD). The torrefaction process enhances the energy density of kesambi leaves by increasing fixed carbon content while reducing volatile matter. The RSM-CCD models developed in this research are both statistically significant and exhibit robust predictive accuracy for estimating higher heating value (HHV), providing valuable insights into optimal torrefaction conditions. Surface plots effectively illustrate the relationships between HHV, temperature, and residence time, enabling the identification of ideal process parameters. Additionally, a desirability analysis reveals opportunities to enhance correlations between HHV and key measured properties, such as moisture content, ash, and volatile matter. This research makes a significant contribution to understanding and optimising the torrefaction process for kesambi leaves, with practical implications for improving energy density and advancing the development of sustainable biofuel sources. By offering a novel approach to predicting HHV in kesambi leaf-based biofuels, the findings highlight the potential for optimising torrefaction processes to enhance the viability of renewable energy resources. Further research is suggested to refine these predictive models and explore additional factors influencing HHV, aiming to bolster the production of sustainable biofuels.

A combination of acetic acid and deep eutectic solvent pretreatment on poplar for coproduction of bioethanol, bio-oil and energy recovery

This work proposed an acetic acid (AC) pre-hydrolysis and a deep eutectic solvent (DES) post-delignification strategy for efficient fractionation of hemicellulose and lignin from lignocellulosic biomass, providing an easily hydrolyzed cellulose, which could be effectively converted to ethanol through semi-simultaneous saccharification and fermentation (SSSF) process. Results showed that, 11.20 kg xylo-oligosaccharides (XOSs), 19.91 kg ethanol and 25.89 kg lignin could be produced from lignocellulosic biorefinery based on the AC-DES pretreatment of 100 kg poplar. In addition, the lignin recovered from DES showed the potential as feedstock for production of hydrocarbon enriched bio-oil by pyrolysis. Higher heating values (HHV) of 27.19 MJ/kg and 31.56 MJ/kg for oil were measured, after pyrolysis of DES lignin and DES lignin/low-density polyethylene (LDPE) with ratio of 7:3, respectively. Finally, mass balance and energy analysis revealed that, lignocellulosic biorefinery based on AC-DES combined pretreatment to co-produce XOSs, bioerthanol and DES lignin could achieve an energy recovery of 78 %.